Energy efficiency via dynamic facades
An adaptable building exterior on a town house in northern Germany is designed to provide an energy supply comparable to that of a ‘passive house’. In addition, the intention is for it to develop more primary energy than it actually needs.
The six models are between 80 and 170m² and are designed by local architectural office p.sindram as generously sized maisonette apartments. Open floor plans and large windows, offering views of the Baltic inlet Schlei, will characterise the layout. Despite the open spaces and high exposure to light, an impressive energy balance is expected, thanks to an adaptable building envelope, which will comprise so-called ‘functional layers’. “The façade is constantly changing and moving because of the different layers, just like the person occupying it,” explains architect Paul Sindram. The layered design includes opaque and transparent elements, which can be moved around on top of each other according to the time of day and weather conditions. Overall, the system is made up of a thermo-active wall and three sheets, which can be coated with a maximum of three different functional layers: insulation, thin film, photovoltaic and sun-protection.
These sheets can be pushed in front of the window openings to fulfil their respective functions. At night, the insulation layer closes, reaching – in combination with the other energy-related components of the house – u-values of up to 0.45 W/m²K. During the day, the sun-protection layer means that the rooms do not heat up too much during intense sunshine. Its tiny aluminium fins allow enough light into the room, meaning that a view of the outside remains with a transparency of 35%. The thermo-active wall reduces heat usage - which is covered by the district heating system - via its integrated ventilation device and heat recovery characteristics. The yearly heat consumption of the compact structure is expected to be 15 kWh/m²a – almost the level of passive houses – as well as also requiring just a small amount of primary energy.
While passive houses often feature large windows on the southern façade, this townhouse also boasts generous openings on the northern, eastern and western sides as well, thanks to a dynamic façade system from Schüco. The eastern façade features large windows of up to 2.5m x 2.9m, while the western side alternates both narrow and wide openings. To the north, there is a staircase that features passive-house-certified aluminium façade elements. Energy plays a key role in the design of the southern side: nine large, fully integrated photovoltaic thin-film elements, which are placed in front of the fixed opaque sections, generate a large proportion of the energy. The east- and west-facing facades support energy creation via seven small PV modules. In the thermo-walls, honeycomb panels filled with hydrated salt store warmth via phase transition, emitting it later on. This means they offer temperature regulation, leading to a pleasant room climate.
In total, the integrated photovoltaic elements, combined with a thin-film photovoltaic system on the roof, should generate more primary energy than the house actually needs. This extra energy can then be stored in the local power work.